The official Â release notes are missing can be found here, but and there is a blog posting about Â the new and noteworthy features/ changes:

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Preview of Super Dev Mode

Introducing Elemental

Speed and Optimization Improvements

ARIA

UiBinder and CellWidget Enhancements

Citing Ray Cromwell from the GWT team about Elemental:

Itâ€™s basically a new API for GWT that is â€žto the metalâ€œ. It is not hand written, but completely generated by the W3C machine readable IDL specs which are used by Chrome and Firefox to implement the C++/Javascript API bindings.This means GWT will have 100% feature parity with hand written JS. There will be no API not exposed. In fact, even experimental stuff like MouseLock, Web Components/Shadow DOM and Web Intents is exposed. And of course, Typed arrays, WebGL, WebAudio, WebSockets, WebRTC, WebWorkers, and pretty much everything else.

Just for the curious: if you donâ€™t know how bare â€žto the metalâ€œ elemental is, have a look here. In my opinion, Â it is nothing I would like to be building apps with, but it is the best we can get to build components with. And it is a change of course: this is something that is really leaving old browsers behind, meaning that we developers must start developing more defensively.

[update1]

There recording of the session is not available yet, but the slides of the presentation can be found on google docs.

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Taking GWT 2.5 RC1 to a ride on an existing project was not a problem at all. The compile settings did not change, and none of my code complained about the new version.

So nothing new? Not really! One of the big news to GWT 2.5 is that the closure compiler was integrated into GWT.

Compiling the app with a few optimizations turned on, I managed to reduce the size of the compile output by almost 50%!!!